InCallService: getService during onCreate

Since there is no guarantee for when onBind will be called, we cannot
use it to initialize critical systemService

Bug: 330247213
Fix: 330247213
Test: atest BluetoothInstrumentationTests:BluetoothInCallServiceTests
Test: atest BluetoothInstrumentationTests:CallInfoTest
Flag: Exempt refactor
Change-Id: I29459364d9425fef6b8b7ece8b5ff6a072f23bc3